Direct Water Splitting under Visible Light with a Nanostructured Photoanode and GaInP2 Photocathode

Thin films of hematite nanorod and GaInP₂ were used for direct water splitting under visible light. In open circuit conditions, the potential of hematite shifted cathodically and that of GaInP₂ anodically, which generated an open circuit voltage between the two electrodes. In short circuit condition, the combination of the two photoelectrodes can split water under visible light illumination, though with a very low current of μA/cm ² level even at 1 W/cm² light. By means of chopped light, we found that hematite nanorod has a low photocurrent, which is responsible for the low short circuit current of the 2-electrode combination. The low photoresponse of hematite nanorods is due to the recombination of photo-generated charges, low holes mobility, and short diffusion length.